Stable antiplaque dentifrice

ABSTRACT

A chemically and physically stable antiplaque dentifrice comprising an antiplaque quaternary ammonium compound, a betaine surfactant, a humectant system of glycerin and/or sorbitol and a nonionic gelling agent, prepared by a process which comprises the preparation of two separate gel phases, an oil gel phase and a water gel phase, combining said gel phases into a single gel, and adding a dental abrasive thereto as the final step, or adding said abrasive to the water gel phase prior to the addition of the oil gel phase.

This is a continuation of application Ser. No. 648,926 filed Sept. 10,1984, now abandoned.

BACKGROUND AND PRIOR ART

The present invention relates to the formulation of an antiplaquedentifrice with improved foaming, improved taste, solubilized activeingredient, improved fluoride stability, improved compatibility of allcomponents, improved extrusion characteristics from various containersand increased cost effectiveness.

Until now it had been difficult to formulate a cosmetically acceptableantiplaque dentifrice consisting of a quaternary ammonium compound and abetaine surfactant with a humectant system of all glycerin or allsorbitol. In addition, the use of mixtures of glycerin/polyethyleneglycol or sorbitol/polyethylene glycol, where glycerin or sorbitol werepresent in excess of 10% by weight of the formulation, displayedmarginal cosmetic stability. However, after extensive solubility testson various mixtures of the components in the benzethonium chloride (BTC)dentifrice, a compatible system of water, BTC, betaine, salts andglycerin was found which was dependent upon the order of addition ofthese components.

Accordingly, it has been found that by using a specific process, stableformulations of an antiplaque dentifrice containing a quaternaryammonium compound and a betaine surfactant can be made with glycerin orsorbitol as the humectant. The essential features in this process is theformation of two separate phases with the subsequent combination ofthese two phases to form the stable system. One of these phases containsthe active quaternary ingredient (benzethonium chloride or cetylpyridinium chloride) solubilized in the betaine surfactant(cocamidopropyl betaine) and a flavor, which is designated the oil gelphase. The second phase contains water, humectant, and nonionic gellingagent e.g. hydroxyethylcellulose, and optionally sodium saccharin andfluorine-containing compound i.e. sodium monofluorophosphate, and isdesignated the water gel phase. The dental polishing agent may be addedto the combined phases as a final step, or be added to the water gelphase prior to combining with the oil gel phase. The finished producthas improved chemical and cosmetic stability and improved taste.

A conventional method of preparing antibacterial dentifrices containinga quaternary ammonium compound as the active material is disclosed inU.S. Pat. No. 4,118,476 and U.S. Pat. No. 4,188,372, and comprises theformation of a gel with humectant (glycerin, sorbitol, polyethyleneglycol), thickener (hydroxyethylcellulose), and sweetener, and addingthereto polishing agent, flavor, antibacterial agent, additional water,and lastly an antistain agent (a phosphono-containing compound or amellitic acid-containing compound).

The prior art also discloses processes for stabilizing a dentifriceagainst precipitation and floculation due to the incompatibility of anantibacterial agent and an alkali metal carboxyalkyl cellulose, as shownin U.S. Pat. No. 3,842,168 and U.S. Pat. No. 3,843,779. The formerpatent utilizes the steps of adding the antibacterial agent dissolved inwater to a nonaqueous blend of the carboxymethylcellulose, sodiumsaccharin and humectant and then adding the surfactant to form a gel, towhich is added the polishing material and flavor as a final step. Thelatter patent adds the antibacterial agent separately or cojointly withthe surfactant to a mixture of glycerin, water, sodium saccharin,carboxymethylcellulose and surfactant, followed by the addition of apolishing material and flavor. The addition of the surfactant mustprecede or be simultaneous with the antibacterial addition in order toavoid precipitation in the dentifrice.

However, the prior art does not disclose a cosmetic, and chemicallystable antiplaque dentifrice containing as the essential ingredients, aquaternary ammonium antiplaque compound, a zwitterionic betainesurfactant, a glycerin and/or sorbitol humectant, and a nonionic gellingagent prepared by a novel process utilizing a specific sequence ofsteps, which comprises the formation of two separate gel phases, an oilgel phase consisting of the quaternary ammonium compound, betainesurfactant and flavor; and a water gel phase consisting of water,humectant and gelling agent; combining the two gel phases into a singleparent gel, and adding a dental abrasive to the combined gel phase as afinal step or to the water gel phase prior to the addition of the oilgel phase.

SUMMARY OF THE INVENTION

It has now been found that stable formulations of an anti-plaquedentifrice containing a quaternary ammonium compound, and a betainesurfactant, can be made with glycerin or sorbitol as the humectant byutilizing a specific sequence of steps which comprises the formation ofa separate oil gel phase of the quaternary ammonium compound, betaineand flavor, a separate water gel phase of humectant, nonionic gellingagent and water (which may preferably contain the salts, i.e. sodiumsaccharin and sodium monoflurophosphate or other fluoride salt),combining the oil and water gel phases to form a stable parent gelphase, and adding a dental abrasive as the final step. This process maybe varied by adding the polishing agent to the water gel and then addingthe oil gel to the water gel-abrasive mixture. This dentifrice isprepared at ambient temperature, i.e. each step in the total sequence ofsteps is performed at ambient (room) temperature.

Accordingly, a primary object of the present invention is to formulate astable antiplaque dentifrice based on quaternary active ingredients, anda betaine surfactant, with improved compatibility of all components, bythe formation of two separate gel phases, which are combined to form astable total gel system.

Another object of the present invention is to provide a cosmetically andchemically stable antiplaque dentifrice containing glycerin and/orsorbitol as humectant which is compatible with the betaine and thequaternary active ingredients.

Still another object of this invention is to provide a stable antiplaquedentifrice containing a nonionic gum, such as hydroxyethylcellulose, asgelling agent to stabilize the betainequat system and to preventdeactivation of the quaternary active ingredient.

Another object of this invention is to provide a cosmetic (physical) andchemically stable antiplaque dentifrice also containing afluoride-providing compound, without adversely affecting cosmeticstability of the dentifrice.

Additional objects, advantages and novel features of the invention willbe set forth in part in the description which follows, and in part willbecome apparent to those skilled in the art upon examination of thefollowing or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and attained by means ofthe instrumentalities and combinations particularly pointed out in theappended claims.

To achieve the foregoing and other objects and in accordance with thepresent invention, as embodied and broadly described herein, the novelstable antiplaque dentifrice of this invention comprising a quaternaryammonium antiplaque compound, a zwitterionic betaine surfactant, flavor,and a humectant selected from the group consisting of glycerin, sorbitoland mixtures thereof, and a nonionic gelling agent is prepared atambient temperature by the process which comprises the formation of twoseparate gel phases, an oil gel phase consisting of the quaternaryammonium antiplaque compound, the betaine and a flavor; and a water gelphase consisting of water, humectant and nonionic gelling agent;combining the two gel phases to form a single gel phase; adding a dentalabrasive to said combined gel phase. The sequence of addition may bevaried by adding the dental abrasive to the water gel phase prior tocombining with the oil gel phase. However, it is essential that twoseparate gel phases be prepared prior to the addition steps. Theaddition of salts such as a fluorine-containing compound and/or sodiumsaccharin, which are preferred components, is made by dissolving in theformula amount of water prior to mixing the water with the humectant andgelling agent in the formation of the water gel phase.

More specifically, present invention relates to a novel process ofpreparing a cosmetic and chemically stable antiplaque dentifriceconsisting essentially of the formation of two phases, an oil gel phaseand a water gel phase comprising the following sequence of steps:

a. dispersing the formula amount of a quaternary ammonium antiplaqueagent in the formula amount of flavor,

b. mixing said quaternary ammonium-flavor dispersion into the formulaamount of betaine surfactant to form the oil gel phase,

c. dispersing the formula amount of nonionic gelling agent in theformula amount of glycerin and/or sorbitol humectant,

d. mixing said gelling agent-humectant dispersion with the formulaamount of water to form the water gel phase,

e. combining the two gel phases to form a stable parent gel phase,

f. adding the dental abrasive to the water gel phase or to the parentgel phase with mixing, and

g. recovering a stable antiplaque dentifrice.

The oil gel phase is in the form of a viscous, translucent gel. Thewater gel phase is transparent. The stable parent gel phase resembles anemulsified system.

This process may be modified by adding and mixing the dental abrasivewith the water gel phase, and then adding the oil gel phase to themixture of dental abrasive and water gel phase.

Sodium saccharin and/or a fluorine-containing compound, which areoptionally preferred additives, are dissolved in the formula amount ofwater prior to its addition to the humectantgelling agent dispersion andthe formation of the water gel phase.

The new formulation method of instant invention using only glycerinand/or sorbitol humectant in a quaternary-betaine system provideschemical and cosmetic stability to the dentifrice as well as improvedtaste. The taste characteristics of a 20% containing-glycerin orsorbitol humectant, benzethonium chloride (BTC), betaine dentifrice aregreatly improved when compared to a 20% polyethylene glycol (PEG 600)BTC dentifrice. The stability afforded by the glycerin and/or sorbitolhumectant does not extend to other humectants such as polyethyleneglycol. A precipitate has been observed in the 20% PEG 600 humectant gelphase of the BTC dentifrice. The precipitate was analyzed using an I.R.spectrophotometric method and was found to be comprised of BTC,saccharin and betaine.

Fluoride stability studies on the BTC dentifrice have confirmed that alarge part of MFP loss is due to hydrolysis in an all PEG 600 humectantsystem. Other phenomena (i.e. adsorption or insolubilization) may beresponsible as well. A solubility problem with PEG 600 andmonofluorophosphate (MFP) has been found. Stability studies of MFP inthe BTC dentifrice indicate that hydrolysis of MFP occurs to a largeextent in an all PEG 600 humectant system. However, an all glycerinhumectant system in the BTC dentifrice displays much less loss of MFP.In fact an all glycerin humectant system meets the present requirementfor MFP shelf life (more than 600 ppm total soluble fluoride, half ofwhich is MFP) while an all PEG 600 humectant system does not (see TableI below).

                                      TABLE I                                     __________________________________________________________________________    MFP Stability in BTC Dentifrice With 20% PEG                                  600 Humectant System and 20% Glycerin Humectant System                        pH         Soluble F   Ionic F    MFP as F                                    Humectant                                                                           I 9w*                                                                              I  3w 6w 9w*                                                                              I 3w 6w 9w*                                                                              I  3w 6w 9w*                                __________________________________________________________________________    PEG   8.2                                                                             10.1                                                                             980                                                                              660                                                                              570                                                                              520                                                                              57                                                                              289                                                                              439                                                                              431                                                                              920                                                                              370                                                                              130                                                                              <100                               Glyc. 7.8                                                                              8.3                                                                             980                                                                              870                                                                              790                                                                              790                                                                              26                                                                               55                                                                               85                                                                              106                                                                              950                                                                              810                                                                              700                                                                               680                               __________________________________________________________________________     *w = weeks                                                               

This table clearly shows the poor stability of MFP in an all PEG 600humectant and the very good stability of MFP in an all glycerinformulation.

HPLC (High Pressure Liquid Chromatography) analysis on both a glycerinand a sorbitol BTC dentifrice formulation was performed initially andafter nine weeks accelerated aging at 49° C. Two extraction methods forBTC (water and acetone) indicate no decrease in BTC recovery afteraccelerated aging (see Table II).

                  TABLE II                                                        ______________________________________                                        HPLC Analysis On A Glycerin And A Sorbitol BTC Dentifrice                     Formulation Initially And After Nine Weeks                                    Accelerated Aging (49° C.)                                                    Initial Analysis                                                                            Analysis After Aging                                              Water     Acetone   Water   Acetone                                  Humectant                                                                              Extraction                                                                              Extraction                                                                              Extraction                                                                            Extraction                               ______________________________________                                        20% Glycerin                                                                           0.42      0.54      0.47    0.52                                     20% Sorbitol                                                                           0.36      0.48      0.45    0.46                                     ______________________________________                                    

The glycerin and/or sorbitol humectant system constitutes about 18-23%by weight of the dentifrice composition.

Cationic antibacterial materials are well known in the art. See, forinstance the section on "Quaternary Ammonium and Related Compounds" inthe article on "Antiseptics and Disinfectants" in Kirk-OthmerEncyclopedia of Chemical Technology, 2nd edition (Vol. 2, pp. 632-635),incorporated herein by reference. Cationic materials which possessantibacterial activity (i.e. are germicides) are used against bacteriaand have been used in oral compositions to counter plaque formationcaused by bacteria in the oral cavity.

Among the most common of these antibacterial antiplaque quaternaryammonium compounds is benzethonium chloride, also known as Hyamine 1622or diisobutylphenoxyethoxyethyl dimethyl benzyl ammonium chloride, andcetyl pyridinium chloride. In an oral preparation this material ishighly effective in promoting oral hygiene by reducing formation ofdental plaque and calculus, which is generally accompanied by areduction in periodontal diseases. Other cationic antibacterial agentsof this type are those mentioned, for instance, in U.S. Pat. Nos.2,984,639, 3,325,402, 3,431,208 and 3,703,583, British Pat. No.1,319,396.

Other antibacterial antiplaque quaternary ammonium compounds includethose in which one or two of the substituents on the quaternary nitrogenhas a carbon chain length (typically alkyl group) of some 8 to 20,typically 10 to 18, carbon atoms while the remaining substituents have alower number of carbon atoms (typically alkyl or benzyl group), such as1 to 7 carbon atoms, typically methyl or ethyl groups. Dodecyl trimethylammonium bromide, benzyl dimethyl stearyl ammonium chloride, cetylpyridinium chloride and quaternized5-amino-1,3-bis(2-ethylhexyl)-5-methyl hexa hydro-pyrimidine are typicalquaternary ammonium antibacterial agents.

The dentifrice formulation of present invention contains an effectiveamount of the antiplaque quaternary ammonium compound, preferably about0.1-1% by weight of the composition.

The ability of quaternary ammonium compounds to inhibit the formation ofdental plaque is well known. However, they are deactivated by theanionic surfactants such as sodium lauryl sulfate conventionally used indentifrice formulations. The substitution of nonionic surfactants forthe anionic surfactants eliminates the deactivation problem but resultsin products with poor foaming. However, the incorporation of betainesurfactants into antiplaque dental formulations based on quaternaryactive ingredients unexpectedly improves the foaming of theseformulations without deactivating the quaternary antibacterial agents.

The betaine component of present dentifrice composition has the generalformula: ##STR1## wherein R₁ is an alkyl group having 10 to about 20carbon atoms, preferably 12 to 16 carbon atoms or the amido radical:##STR2## wherein R is an alkyl group having about 10 to 20 carbon atomsand a is the integer 1 to 3; R₂ and R₃ are each alkyl groups having 1 to3 carbons and preferably 1 carbon; R₄ is an alkylene or hydroxyalkylenegroup having from 1 to 4 carbon atoms and, optionally, one hydroxylgroup. Typical alkyldimethyl betaines include decyl betaine or2-(N-decyl-N,N-dimethylammonio)acetate, coco betaine or2-(N-coco-N,N-dimethylammonio)acetate, myristyl betaine, palmitylbetaine, lauryl betaine, cetyl betaine, stearyl betaine, etc. Theamidobetaines similarly include cocoamidoethyl betaine, cocoamidopropylbetaine, lauramidopropyl betaine and the like.

The betaines, which are zwitterionic materials, function as a foamingagent in the quaternary-containing dentifrice compositions. They actcationically over a wide pH range, but do not deactivate the quaternaryantimicrobial activity.

In addition to the non-interference exhibited by the betaines with thequaternary activity, laboratory foam tests have shown that formulationscontaining both the quaternary ammonium compound (quat) and the betaine,foam 2-3 times better than the nonionic/quat formulations.

The zwitterionic betaines are completely compatible with the quaternaryantimicrobial antiplaque agents, and impart detersive and improvedfoaming properties to the quaternary-containing dentifrice compositionwithout deactivating the antimicrobial properties thereof. The amount ofbetaine effective in the production of improved foaming may be variedfrom about 3-5% by weight of the total formulation.

Cosmetic problems of stability is incurred with allzwitterionic-containing dentifrices, such as crimp leakage of flavor.The flavor oozes and is not solubilized in the zwitterionic surfactant.However, stability evaluations of present novel antiplaque dentifricescontaining glycerin and/or sorbitol humectant indicate satisfactoryflavor stability for nine weeks aging at 49° C. The flavor ingredientwhich is an essential ingredient in a dentifrice constitutes about0.5-2% by weight. Any suitable flavor may be employed. Examples ofsuitable flavoring constituents are flavoring oils, e.g., oils ofspearmint, peppermint, wintergreen, sassafras, clove, sage, eucalyptus,marjoram, cinnamon, lemon, and orange, and methyl salicylate.

A sweetening material may also be employed as a complement to theflavoring material. Suitable sweetening agents are water soluble andinclude sucrose, lactose, maltose, sorbitol, sodium cyclamate, andsaccharin, in an amount of 0.01-0.5% by weight.

Another essential ingredient in present dentifrice is a gelling agentwhich is a nonionic gum, in an amount of about 0.8-1.5% by weight. Ithas been found that large organic anionic molecules such ascarboxymethylcellulose have the potential to deactivate the quaternaryantibacterial activity. Accordingly, hydroxyethylcellulose, which is anonionic small organic molecule, effects a stable pituitous gel in thebetaine-quat system of present invention, and is the preferred gellingagent. Other nonionic gelling agents may be used such ashydroxymethylcellulose, and the like.

The fluoride-providing compounds, which are preferably additionalingredients in present dentifrice, are characterized by their ability torelease fluoride ions in water and by substantial freedom from reactionwith other compounds of the dentifrice. Among these materials areinorganic fluoride salts, such as soluble alkali metal, alkaline, earthmetal and heavy metal salts, for example, sodium fluoride, potassiumfluoride, ammonium fluoride, lead fluoride, a copper fluoride such ascuprous fluoride, zinc fluoride, a tin fluoride such as stannic fluorideor stannous chlorofluoride, barium fluoride, sodium fluorosilicate,ammonium fluorosilicate, sodium fluorozirconate, sodiummonofluorophosphate, aluminum mono- and di-fluorophosphate, andfluorinated sodium calcium pyrophosphate. Alkali metal and tinfluorides, such as sodium and stannous fluorides, sodiummonofluorophosphate and mixtures thereof, are preferred.

The amount of the fluoride-providing compound is dependent to someextent, upon the type of compound, its solubility, and the dentifrice,but it must be a nontoxic amount. In a solid oral preparation, such as atoothpaste or dental cream, an amount of such compound which releases amaximum of 1% by weight of the preparation is considered satisfactory.Any suitable minimum amount of such compound may be used, but it ispreferable to employ sufficient compound to release from 0.005% to 1%,and preferably about 0.1% of fluoride ion. Typically, in the cases ofalkali metal fluorides and stannous fluoride, this component is presentin an amount up to 2% by weight, based on the weight of the preparation.In the case of sodium monofluorophosphate, the compound may be presentin an amount up to 7.6% by weight, more typically 0.76%.

The dentifrice prepared in accordance with this invention, containsconventional water-insoluble polishing materials or dental abrasives, inamounts from about 35-65% by weight of the total formulation. Suitableexamples of dental abrasives or polishing materials include sodiummetaphosphate, potassium metaphosphate, tricalcium phosphate, dihydratedcalcium phosphate, anhydrous dicalcium phosphate, calcium pyrophosphate,magnesium orthophosphate, trimagnesium phosphate, calcium carbonate,zirconium silicates, silica, bentonite, and mixtures thereof. Thepreferred abrasives are alumina-containing abrasives such as calcinedalumina and hydrated alumina and mixtures thereof. The abrasive is addedto the water gel phase or to the single gel after combining the oil geland water gel phases.

The dentifrice of this invention may also contain conventionaladditional ingredients such as coloring or whitening agents,preservatives and ammoniated materials such as monoammoniumglycyrrhizinate. These additional ingredients may each be added to thedentifrice in minimal amounts of up to 5% by weight, and preferably upto 1%, provided they do not interfere with the foaming, antiplaque andstability properties of the finished product. The oil phase typicallyconstitutes about 3.6-8% by weight of the dentifrice.

In the practice of this invention to promote oral hygiene, thedentifrice according to this invention is applied regularly to dentalenamel by brushing the teeth for 30-90 seconds at least once daily.

DETAILED DESCRIPTION OF THE INVENTION

The following examples are further illustrative of the nature of thepresent invention, but it is understood that the invention is notlimited thereto. The compositions are prepared in the usual manner andall amounts and proportions referred to herein and in the appendedclaims are by weight unless otherwise indicated.

EXAMPLE 1 Glycerin Humectant Anti-Plaque Dentifrice

    ______________________________________                                        Ingredients          %                                                        ______________________________________                                        Water (Deionized)    19.34                                                    Sodium Saccharin     0.30                                                     Sodium Monofluorophosphate                                                                         0.76                                                     Hydroxyethylcellulose                                                                              1.10                                                     Glycerin             20.00                                                    Benzethonium Chloride                                                                              0.50                                                     Flavor               1.00                                                     Cocamidopropyl Betaine                                                                             5.00                                                     Calcined Alumina     10.00                                                    Hydrated Alumina     42.00                                                    ______________________________________                                    

The benzethonium chloride is dispersed in the flavor and this dispersionis mixed into the betaine to form an oil gel. The sodium saccharin andsodium monofluorophosphate (MFP) are dissolved in the water.Hydroxyethylcellulose is dispersed in the glycerin, and this mixture isadded to the water-saccharin-MFP solution with stirring to form a watergel. The oil and water gels are mixed to form a stable parent gel. Thecalcined alumina and hydrated alumina are admixed with the parent gel toproduce the finished dentifrice which is effective against plaquerelated bacteria while possessing excellent chemical and cosmeticstability as well as having sufficient foaming characteristics. Thisdentifrice is prepared at room temperature.

EXAMPLE 2

Example 1 is repeated except that 20% sorbitol is substituted for the20% glycerin. The resultant product is equally effective against plaquerelated bacteria and also possess excellent chemical and cosmeticstability and sufficient foaming properties.

MFP stability studies indicate that both the new glycerin and sorbitoldentifrices have an excellent MFP stability profile. Example 1 (20%glycerin) had an initial total soluble fluoride value of 990 ppm and anMFP as F value of 950 ppm. Example 2 (20% sorbitol) had an initial totalsoluble fluoride value and an MFP as F value of 1,020 ppm and 980 ppmrespectively (See Table III).

TABLE III MFP Stability Profile of a New All Glycerin BTC Dentifrice anda New All Sorbitol BTC Dentifrice (Nine Weeks (w) Aging at 49° C.)

    ______________________________________                                                  pH    Soluble F Ionic F  MFP as F                                   Ex.  Humectant  I     9w  I    9w   I    9w  I    9w                          ______________________________________                                        1    All Glycerin                                                                             7.8   8.0  990 820  43   94  950  730                         2    All Sorbitol                                                                             7.6   7.7 1020 960  43   45  980  910                         ______________________________________                                    

The pH profiles of both formulations showed only a slight increase afternine weeks aging at 49° C. After accelerated aging, values for totalsoluble fluoride and MFP as F were 820 ppm and 730 ppm respectively forExample 1 and 960 ppm and 910 ppm respectively for Example 2.

Variations in the above formulations may be made. For example, otherbetaines such as lauramidopropyl betaine, cocobetaine and the like maybe substituted for the cocoamidopropyl betaine in the examples.Similarly, other abrasives may be substituted for the specific abrasivesin the examples. Likewise, other fluoride-containing compounds such assodium fluoride, potassium fluoride, etc. may be substituted for thesodium monofluorophosphate in the specific examples. Likewise, cetylpyridinium chloride or other quaternary ammonium antiplaque agents maybe substituted for the benzethonium chloride. Also, sodium cyclamate mayreplace sodium saccharin.

It is understood that the foregoing detailed description is given merelyby way of illustration and that variations may be made therein withoutdeparting from the spirit of the invention. The "Abstract" given aboveis merely for the convenience of technical searchers and is not to begiven any weight with respect to the scope of the invention.

We claim:
 1. A process of preparing a cosmetic and chemically stableaqueous fluoride-containing antiplaque dentifrice comprising aquaternary ammonium antiplaque compound, a betaine surfactant, flavor,glycerin and/or sorbitol humectant, and a nonionic gelling agent, whichcomprises the formation of two separate gel phases, an oil gel phaseconsisting essentially of the quaternary ammonium compound, the betainesurfactant and flavor; and a water gel phase consisting essentially ofwater, humectant and gelling agent; dissolving a fluorine-containingcompound in the formula amount of water prior to the addition of thewater to the humectant and gelling agent in the formation of the watergel phase; combining said two separate gel phases into a single gelphase; and adding a dental abrasive to said combined single gel phase orsaid water gel phase prior to the addition of the oil gel phase.
 2. Aprocess according to claim 1, wherein the fluoride-providing compound ispresent in an amount sufficient to release about 0.005-1% by weight offluoride ion to the dentifrice.
 3. The process according to claim 2,wherein the fluoride-providing compound is sodium monofluorophosphate.